Calcium lactate is a white crystalline salt with chemical formula [CH3CH(OH)COO]2Ca. Calcium lactate exists in various forms: anhydrous amorphous material, crystalline pentahydrate and mixtures thereof.
Calcium lactate is used in calcium fortification of juices and juice drinks, nectars, non-clear beverages, acidified dairy/soy drinks, powdered drinks, infant food and is formulated into capsules, tablets and liquids as therapeutic or nutritional supplement. Furthermore, calcium lactate is used as a food preservative.
The calcium lactate products that are commercially available are generally obtained by mass crystallisation followed by grinding or by spray drying. The calcium lactate powders so obtained typically contain high levels of calcium lactate pentahydrate. Calcium lactate in the crystalline pentahydrate form has favourable dispersion properties so that it can very easily be dissolved in water. However, in mixtures containing calcium lactate, presence of water of hydration is also a disadvantage because the water can be extracted from the crystal by other components that are hygroscopic in nature. Take-up of moisture originating from calcium lactate pentahydrate by such hygroscopic components, can result in the entire product becoming sticky. Clearly, this negatively affects the properties of the product. To prevent water uptake of the hygroscopic component, calcium lactate should be used in the anhydrous form.
Anhydrous calcium lactate, on the other hand, is notoriously difficult to dissolve in water. When particles of anhydrous calcium lactate come into contact with water these tend to form lumps that dissolve very slowly.
An example of a commercially available calcium lactate pentahydrate powder is PURACAL® PP/FCC (marketed by Purac, now Corbion). This product contains 13.4-14.5% (w/w) calcium and exhibits a loss on drying of 22.0-27.0% (w/w). This particulate material (surface-based average particle size, D[32], of 184 μm) has a solubility in water of 9 g/100 ml at 25° C. The typical dissolution time of this powder is 25 seconds (when 1000 mg of a sample is dissolved in 240 ml water).
US 2011/300220 describes solid calcium lactate in the form of substantially spherical particles, said spherical particles having a particle size distribution such that most of the particles are between 280 and 550 microns in size and the calcium lactate can be rapidly dissolved in water. This US patent application describes a method for the production of these spherical calcium lactate particles, comprising:                in a first step, a calcium lactate solution is atomised in a fluidised bed granulator at an incoming air temperature of less than 80° C.;        the wet substantially spherical calcium lactate particles are retrieved; and        in a second step, said wet particles undergo a heat treatment in a fluidised bed at an incoming air temperature of less than 165° C.        
WO 00/28973 describes process for the preparation of an orally administrable calcium composition, said process comprising the steps of:                obtaining a physiologically tolerable particulate calcium compound having a mean particle size in the range 3 to 40 μm, having a crystalline structure and having a surface area of 0.1 to 1.2 m2/g;        mixing said calcium compound with a water soluble diluent and an aqueous solution of a water soluble binder in a fluid bed granulation apparatus and drying the resulting mixture to produce a granulate.        
US 2008/152764 describes a particulate composition comprising calcium lactate and calcium citrate microparticles having an average diameter from 0.1 μm to 20 μm, wherein the composition is in the form of particles with an average diameter from 25 μm to 1 mm, wherein the ratio by weight of calcium lactate to calcium citrate, based on the dry weight, is 80:20 to 30:70, and wherein the calcium lactate is a non-polymeric agglomeration agent for the calcium citrate microparticles. These particulate calcium lactate containing compositions exhibit good processing properties as well as good dispersion and dissolution behavior.